St. Elmo's Fire
From RationalWiki
St. Elmo's Fire is a weather phenomenon that has probably sparked more ghost stories than all the other myths combined[citation needed] (and also a "Brat Pack" movie). One thing St. Elmo's Fire isn't is fire.
St. Elmo's Fire is — like lightning — plasma, or ionized air, that emits a glow. However, it results not from a movement of charged particles from a cloud to the ground, but rather it's a corona discharge, caused by an imbalance in electrical charges. This imbalance is between the air and an object around it, and as a tapered surface will discharge at a lower voltage level, it occurs most often on the tip of a steeple, mast or aeroplane wing.